Method of increasing the density of



Pmm'd Sept. 8, 1942 "UNITED STATES PATENT OFFICE METHOD OF INCREASINGTHE DENSITY OF A MASS F GRANULAR MATERIAL Donald w. Ross, Washington,Pa.

No Drawing. Original application November 5,-

1938, Serial No. 239,184. Divided and this application July 22, 1939,Serial N0. 285,961

7 Claims. (Cl. 25-156) This invention relates to the production ofmassive bodies from granular material, and consists in a method ofincreasing the density of such bodies. It finds practical application inconcrete building and in the production of articles of ceramic ware andrefractories. It is advantageously employed in the production ofrefractories whose ingredients in finely divided condition aresize-graded according to the teaching of the specification of anapplication for 10 more greatly increased, by subjecting it to furi thatin clay suspensions in water, and other suspending media, suchexchangeable cations. serve as the connections between clay particles;and that, in cases in which such cations bring about coagulation of clayparticles, it tends to be an oriented coagulation. Further, it is knownthat clay-particles in such suspensions can be oriented by passingelectric current through the suspensions and by subjecting thesuspensions to electric fields.

. Reasoning from the above and other known chemical facts, I haveconcluded that such suspended ultimate clay particles, and similarsuspensions of many other kinds of particles, carry, or are capable ofcarrying, electrical charges.

By altering the direction of an electric current 40 that I may cause topass through such a suspension, or by, altering the direction of linesof force. of an electric field to which I may subject such a suspension,it is possible to break down given orientations and form still otherorientations in conformity with the altered directions. Still further,since the ultimate par ticles of such .a suspension can carry electric.

charges, it is possible to orient and -alter the positions of theparticles relative to each other 0 by subjecting the suspension to anyelectric, electronic, magnetic field, electromagnetic induction, orpositive or negative ray forces of sufiicient magnitude. Similarly, bymore or less continuously my earlier 15 sible to keep the ultimateparticles in more or less continuous mcvement relative to one another.By using such forces of sufilcient intensity and by varying theintensity I am able to gain maximum and desirable time of disorientationof ultimate particles and produce other dosirable effects.

Multiple forces of the nature specified may be simultaneously applied;they may be applied in parallel directions or at angles to one another,

in the same plane or in different planes, and

in changing directions relative to one another. I

Conventional means may be employed that the dispersions may bepenetrated by direct or alternatin'g current, or may be brought withinand made subject to magnetic fields, to electro-magnetic induction, orto positive or negative rays. The waves of force may vary, not indirection only, but in intensity as well. In case direct or alternatingcurrent is used directly for this purpose, I prefer to use a current ofbetween 22 and 1500 volts, and, with amperage suitably small, thecurrent becomes relatively safe to handle.

A specific means of accomplishing rapid change of orientation isto-place a mass of the material within an annular coil, so wound thatthe particles within the mass of material will be rapidly oriented andtheir orientation altered when an alternating current is passed throughthe coil. The field intensity is, of course, sufiicient to causeorientation.

'In concrete and in ceramic masses containing granular and colloidalmaterial, I may prefer to cause movement of particles relative to oneanother by causing at least some of the particles to vibrate by means ofpassing high-voltage high! frequency electric current throughpiezo-electric crystals, the piezo-electric materials being situatedeither outsideof or within the mass being acted upon. I may prefer touse Rochelle salt, quartz, mullite, particles that are largely alumina,magnesium chloride, ammonium chloride, magnesium ammonium chloride,ammonium fluoride, ammonium duo-silicate, and other materials, includingconstituents of the ceramic mass, as the piezo-electric material, andvary the frequency and voltage to suit the material used. I may preferso to act on ceramic masses while they are under pressure. Crystallineconstituents of ceramicmasses frequently contain -crystal strain,particularly in fired particles. I may vibrate a dispersion by means ofpiezo-eiectric vibration of these strained particles.

altering the direction of such a force, it is nos lfiezo-electricexcitation may be set up by caus ing particles of quartz present in adispersion to vibrate. Particles'of quartz are normally present in aconcrete mix and in a ceramic casting slip also.

Piezo-electric excitation is commonly carried out by passing theexciting force through the crystal in a given direction. I may prefer toorient piezo-electric crystals in a mass of particles, such as concrete,ceramic materials, and refractory materials by the methods hereof; and,while so oriented, to pass a piezo-electric exciting force through suchcrystals in the most favorable direction. For instance, I may prefer so.to orient particles of quartz, kyanite, clay, magnesite, chrome,and'auxiliary piezo-electric materials, including organic piezo-electricmaterials, and to subject them to piezo-electric exciting force while sooriented.

In case the two sets of forces interfere, I may prefer to apply themalternately to the piezoelectric particles. In case alternatingelectrical forces are used for this purpose, I may choose to synchronizethese forces, so that one is acting with minimum effect on the particleswhile the other'is .acting with-maximum effect. For instance, one forcemight be one fourth of a cycle behind the other.

I may prefer to use this piem-electric crystal vibration method in theforming of concrete masses and of ceramic masses containing mini-- mumwater contents, whether the ceramic mass be shaped by slip casting, bypressing, or by other forming method. I

By subjecting the particles of the suspension to such orienting andpiezo-electric influences rigidity of a mass may be diminished, facilityof flow increased, and other good purposes served.

One specific practical application of the invention is found indecreasing the rigidity of water-containing masses of concrete, so thatthey can be flowed to position and form a relatively void-free finishedproduct. Another application is found in doing the like in the case of aceramic mass, so that the mass, containing an amount of water less thanotherwise is practi- In ceramic masses, such control of orientation ofultimate particles has the advantage that it permits of wider variety inthe applications of a 7 number of ceramic materials. Specifically, itpermits the use of certain clays in slip-cast ware that give unusualstrength to the ware, and

' whose'particle-size range apparently is unusually cable, may still beflowed into a mold, or otherwise shaped. I find a result ofdisorientation of particles in ceramic and other masses to be lowporosity of the formed dried masses.

In particular cases I prefer to keep the particlesdisoriented only longenough to permit formgreat.

I may in particular cases and with good effect disorientthe silicaparticles of silica jellies.

The combined result of this invention with particle-size gradingaccording to the teaching of my earlier application named above is a dryporoslty of ware which, to my knowledge and belief, is lower than hasheretofore been achieved, either by slip casting or by any other method.

In the manufacture of cement, specifically, not only may the strengthand covering power of the cement be improved by extending according tomy formula the lower limits of particle size, but also (since concretecommonly contains quartz particles that can be piezo-electricallyexcited)- such excitation may be resorted to in order to increase thefluidity of the newly mixed mass.

I claim as my invention:

1. The method herein described of increasing the density of a mass ofgranular material which consists in subjecting the mass to successive,differently directed polarizing stresses.

2. The method herein described of filling a mold with slip, whichconsists in subjecting the slip as it comes to place in the mold tosuccessive, diiferently directed polarizingstresses.

3. The method herein described of increasing the density of a mass ofgranular materials that consists in part of grains that manifest thepiezoelectrical phenomenon and ability to be electrically oriented 'andin part of grains that do not manifest such phenomenon nor such ability,which consists in subjecting the mass to the in-.

fluence of an electro-magnetic field, and repeatedly varying themagneticeifect of the field and producing in the masspiezo-electrical-vibration-' producing stresses.

4. The method herein described of increasing the density of a mass ofgranular material which consists in subjecting the mass to polarizingstresses, and repeatedly varying the intensity 'of such stresses. l

' 5. The method herein described offilling a mold with slip, whichconsists in subjecting the ing (as in a mold) the masses containingthem.

The particles may then be re-oriented, for the purpose of'giving to themolded material a set,

so that the molded article can be removed from the mold within a minimumperiod of time, and so that other useful purposes can be served. Themolding may be performed by slip casting. Dressing, or by other suitablemeans.

' Referring again to the crystal structure of clay particles, it iscommonly known that the molecules .of polar liquids, such as water,attach themselves to the ultimate particles of suspensions in definitelyoriented positions with reference to the cation bonds between theparticles. Reasoningfrom this and other known chemical facts, such wateris, I believe, little attached to and hence more easily removed fromdisoriented particles than from oriented material. I, therefore, preferto alter the orientation of ultimate particles and to disorient themduring .at least part of the time of the dryingof masses containingthem! Such treatment serves to permit easslip as it comes to place inthe mold to polarizing stresses, and repeatedly varying the-intensity ofsuch stresses.

6. The method herein described of increasing the density of a mass ofsize-graded granular materials including in part grains that manifestthe piezo-electrical phenomenon and in part grains that do not manifestsuch phenomenon, which method consists in subjecting the mass todifferently directed electrical forces and producing in the masspiezo-electrical vibration-producing stresses.

'7. The method herein described of increasing the density of a mass ofsize-graded granular materials including in part grains that manifestthe piezo-electrical phenomenon and in part grains that do not manifestsuch phenomenon, which method consists in subjecting the mass toelectrical forces, repeatedly varying the intensity of such forces andproducing in the mass piezo-electrical vibration-producing stresses.

DONALD W. ROSS.

